MMOX/SL assets
Primitives
Prims are meshes, mostly 3D, although Sculpted Prims can be 2-dimensional.
Objects
Objects are formal groups of prims, linked to each other, with one prim in the object set defined as "root"
Objects used to have the ability to group themselves in a slightly less formal way via Joints
Textures
Textures are raster images.
Sculpted Prims
Sculpted prims require a specially formulated texture in order to be "sculpted".
Photos
SL Inventory seems to make a distinction between textures and Photos (images saved to file of what the viewer was rendering at a given moment in time).
Animations
Animations are supported by composting each frame of an animation sequence into a single tile.
Sounds
Animations
Notecards
Plain text documents that can have other assets embedded within them.
Scripts
LSL code in a plain text file for editing. Scripts can only "run" while existing in a prim's inventory, though they can be stored in a non-running state in both prim and Resident inventories.
Gestures
Gestures can have sounds and animations applied to them.
Body Parts
Body parts can have textures applied to them.